Reapply "New implementation of {,Linked}Hash{Set,Map}."

sdk/lib/io/http_impl.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of dart.io;
 
 // The close queue handles graceful closing of HTTP connections. When
 // a connection is added to the queue it will enter a wait state
 // waiting for all data written and possibly socket shutdown from
 // peer.
@@ skipping 1899 matching lines @@
   }
 
   set sendClientCertificate(bool send) => _sendClientCertificate = send;
 
   set clientCertificate(String nickname) => _clientCertificate = nickname;
 
   set findProxy(String f(Uri uri)) => _findProxy = f;
 
   void shutdown({bool force: false}) {
     if (force) _closeQueue.shutdown();
-    _openSockets.forEach((String key, Queue<_SocketConnection> connections) {
+    new Map.from(_openSockets).forEach(
+        (String key, Queue<_SocketConnection> connections) {
       while (!connections.isEmpty) {
         _SocketConnection socketConn = connections.removeFirst();
         socketConn._socket.close();
       }
     });
     if (force) {
-      _activeSockets.forEach((_SocketConnection socketConn) {
+      _activeSockets.toList().forEach((_SocketConnection socketConn) {
         socketConn._httpClientConnection._onClientShutdown();
         socketConn._close();
       });
     }
     if (_evictionTimer != null) _cancelEvictionTimer();
     _shutdown = true;
   }
 
   void _cancelEvictionTimer() {
     _evictionTimer.cancel();
@@ skipping 386 matching lines @@
 
 
 class _RedirectInfo implements RedirectInfo {
   const _RedirectInfo(int this.statusCode,
                       String this.method,
                       Uri this.location);
   final int statusCode;
   final String method;
   final Uri location;
 }